Yeast Vaccine Could Be Used To Immunize Against Cancers And Infectious Diseases

Vaccines that cause the production of antibodies alone to menacing antigens are not powerful enough to combat diseases such as HIV and cancer. Thus, scientists are currently trying to develop vaccines that stimulate the second half of the immune response called the cell-mediated response. The latter involves the stimulation of cells called cytotoxic T lymphocytes that produce chemicals that kill the offending pathogen. Richard Duke and colleagues at Ceres Pharmaceuticals have developed the prototype for such a vaccine using the simple yeast Nature Medicine (Vol. 7, No. 5, 01 May 01).

The scientists engineered yeast cells to express an HIV antigen. They vaccinated mice with the yeast vaccine and discovered that the cytotoxic T lymphocytes that the mice produced were powerful and specific enough to destroy only those cells containing a fraction of the HIV virus.

The novel yeast vaccine works by activating a group of immune cells called dendritic cells (DC). These cells absorb the yeast and any antigens it is carrying, process the antigens and then present them on the cell surface. This triggers a strong immune reaction which also includes the release of a potent chemical called interleukin-12.

The authors propose that such a yeast vaccine could be used to immunize against several different types of cancers and infectious diseases.